1. Field of the Invention
The present invention relates to a tool for machining a workpiece. The present invention relates in particular to a straight turning tool.
2. Related Prior Art
In known tools of this type, the cutting tool, for example a cutting insert, is fastened in the accommodating recess of the tool body by an internal thread being provided in the tool body bore. Engaging in this internal thread is a fastening screw having a corresponding external thread, and this fastening screw engages from the outside first of all through the cutting tool bore in the cutting tool and then engages in the tool body bore and is then tightened.
However, in straight turning automatic lathes, in which such tools, “straight turning tools”, are frequently used, there is often little space for exchanging the cutting tool, which is a wearing part and frequently has to be changed, while the tool body remains clamped in the machine tool. However, since the screw with which the cutting tool is fastened to the tool body is only accessible from one side in the known tools, the entire tool, for changing the cutting tool, consequently often has to be removed from the machine tool and re-fitted again after the cutting tool change. This is awkward and leads to long setup times and is therefore to be avoided according to the invention.
A tool in which the fastening means for fastening the cutting tool to a tool body are accessible from two opposite sides and in which the problem described above is already solved in principle is known from WO 2003/074217. In this document, a special fastening element is used for fastening the cutting tool to the tool body, said fastening element having, at the front end thereof, special helical clamping wings which interact like a thread with corresponding support wings inside the cutting tool bore. The cutting tool is in this case fastened to the tool body by screwing this fastening element into the cutting tool bore, although the fastening element has to be turned by means of different keys from both sides for the tightening or release. The use of different keys is awkward and is therefore to be seen as a disadvantage in the manipulation of this tool.
Described in German Patent Application 10 2007 063 199.7-14 (date of filing: Dec. 19, 2007) and in the parallel application WO 2009/077060 A1 is a tool in which the problem described relating to the accessibility of the fastening means from two opposite sides is likewise solved in principle. Here, there is additionally the advantage that the tightening or release of the fastening means from both sides can be effected by means of the same key. The clamping means are realized here by a clamping screw and a clamping bush. So that counter-holding of the clamping bush is not necessary when screwing in the clamping screw and so that said clamping bush does not rotate, in particular a separate locking pin is provided as anti-rotation locking means.